Power transmission shaft

Abstract

A power transmission shaft performs a fuse-like function when excessive torque is applied to a power input side. The power transmission shaft includes: a main shaft connected to a power device; flanges connected to the power device and provided at both sides of the main shaft; and a flexible coupling extending in the radial direction of the main shaft. The power transmission shaft includes a power shutoff unit which shuts off power by breaking the main shaft or the flanges when torque greater than a predetermined level is applied. When excessive torque is applied to the power input side, the power transmission shaft performs a fuse-like function with respect to the excessive torque, thereby enhancing safety, preventing sparks from occurring at the time of the breakage, facilitating the production thereof, and effectively preventing vibration while sufficiently supporting the speed or load in the event of a high rotation rate.

1 - 12 . (canceled) 
     
     
         13 . A power transmission shaft comprising a main shaft to connect a power unit; flanges disposed at both sides of the main shaft to be joined with the power unit; a flexible coupling formed to extend in a radial direction of the main shaft; and a power shutoff unit formed at least one of the main shaft and the flanges to cut off power by breaking the main shaft or the flanges in response to an application of a torque greater than a predetermined level. 
     
     
         14 . The power transmission shaft according to  claim 13 , wherein the power shutoff unit is formed on an outer circumferential surface of at least one of the main shaft and the flanges, and comprising a notch dented inwardly in the radial direction. 
     
     
         15 . The power transmission shaft according to  claim 14 , further comprising a screen formed on an outer surface in the radial direction relative to the notch to cover at least a part of the notch and prevent scattering of sparks. 
     
     
         16 . The power transmission shaft according to  claim 15 , wherein a part of the screen is opened outwardly in the radial direction. 
     
     
         17 . The power transmission shaft according to  claim 16 , wherein the opened part of the screen faces toward the flexible coupling. 
     
     
         18 . The power transmission shaft according to  claim 14 , wherein the notch is formed in at least one of a power input side and a power output side. 
     
     
         19 . The power transmission shaft according to  claim 13 , further comprising a ball joint disposed between the main shaft and the flanges to prevent whirling of the main shaft, the ball joint restricts axial and radial direction movements but allows rotational directional movements between the main shaft and the flanges. 
     
     
         20 . The power transmission shaft according to  claim 19 , wherein the ball joint is fixed at the side of the flanges. 
     
     
         21 . The power transmission shaft according to  claim 19 , wherein a lubricant is disposed on a rotating part of the ball joint. 
     
     
         22 . A power transmission shaft comprising a main shaft to connect a power unit; flanges disposed at both sides of the main shaft to be joined with the power unit; a flexible coupling formed to extend in a radial direction of the main shaft; and a ball bearing disposed between the main shaft and the flanges to prevent whirling of the main shaft, the ball bearing restricts axial and radial directional movements but allows rotational direction movements between the main shaft and the flanges. 
     
     
         23 . The power transmission shaft according to  claim 22 , wherein the ball bearing comprises a housing fixed to the flanges and a bearing disposed between a housing and the main shaft; and wherein the bearing comprises an outer wheel, an inner wheel and a ball, an inner surface of the outer wheel is formed in a shape of a sphere, and a center of the bearing coincides with a central line of the flexible coupling along an axial direction. 
     
     
         24 . The power transmission shaft according to  claim 23 , further comprising stepped portions respectively formed on one side of the housing and one side of the main shaft so that a pre-load is applied when the housing of the ball bearing is joined in the axial direction.